The idea of young blood slowing the aging process is a popular modern myth. A new study, however, suggests it might not be quite as ridiculous as it sounds.

Saul Villeda of Stanford University yesterday presented results which suggest it is possible to rejuvenate the brains of old animals by injecting them with blood from the young. Speaking at the annual meeting of the Society for Neuroscience in New Orleans, he explained that he'd observed blood from young mice could reverse aging effects in older mice. Clearly Kim Jong-il, who's rumored to have injected himself with blood from healthy young virgins to help him through his later years, may have been onto something.

Villeda described a series of experiments where the circulatory systems of an old and young mouse were connected, so their blood was shared. Upon examining the older mouse several days later, he found clear signs of the aging process being reversed: there were more stem cells in the brain, and a 20 percent increase in connections between brain cells. Further experiments showed that even just blood plasma from younger creatures improved cognitive function in the older rodents.

The work's an extension of a previous study which showed that the brains of young mice began to age more rapidly when exposed to blood from older mice. As for the finding's applications in humans, Villeda explained to the Guardian:

"Do I think that giving young blood could have an effect on a human? I'm thinking more and more that it might. I did not, for sure, three years ago."

However, before we all get carried away and start infusing granny with our freshly drawn blood, do bear in mind that this study hasn't been officially published, let alone peer-reviewed. It's a tentative finding, which is why it's been presented at a conference. As Andrew Randall, a professor of applied neurophysiology, explained to the Guardian:

"Although this [research] may suggest that Bram Stoker had ideas way ahead of his time, temporarily plumbing teenagers' blood supplies into those of their great-grandparents does not seem a particularly feasible future therapy for cognitive decline in aging. Instead this fascinating work suggests there may be significant benefit in working out what the 'good stuff' is in the high octane young blood, so that we can provide just those key components to the elderly."

His point highlights the fact that the current research sheds no light on how the young blood reverses effects of aging. If scientists can nail that, though, then they're really on to something. [Guardian]